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Engineering

The advancement of 3D printing

Health and industry applications drive this additive manufacturing technique to grow 25% per year

Detalhe de cabeçotes de impressora finalizando a produção de um cubo moldado com polímero

Custom medical and dental prostheses, complex automotive and aerospace parts, molds, and custom or low-volume consumer goods such as spare parts for off-line equipment—the applications of additive manufacturing technology are becoming more and more widespread. Also known as three-dimensional (3D) printing, the process was developed in the 1980s with the goal of quickly producing three-dimensional prototypes for products. Data from the US consulting firm Wohlers Associates show that between 2013 and 2017 financial revenue generated through additive manufacturing had an annual growth rate of 25%, totaling US$7.3 billion in 2017. The consulting firm estimates that in the coming years the pace of expansion of this production system, which is aimed toward several market segments, will accelerate even more and should yield US$20 billion in annual revenues by 2021.

Eduardo Zancul, a professor of production engineering at the Polytechnic School of the University of São Paulo (Poli-USP), explains that additive manufacturing features the use of equipment called 3D printers. They are capable of making objects by adding material, layer by layer, from a three-dimensional digital model, usually obtained through the use of a computer-aided design (CAD) system.

The concept is the opposite of traditional production methods, such as machining, in which parts are manufactured by removing material, metallic or otherwise, by using machining tools such as lathes and milling machines. “There is more economic use of raw materials, and waste is reduced, since the raw material is deposited according to requirements defined in the programmed model,” the researcher observes, noting that there are several 3D-printing technologies in use today.

Infographic Ana Paula Campos

Regardless of the technique, production is automated and human supervision is required only for the provision of raw material. Among the principal materials in use are high-temperature molded plastic (thermoplastic), resin, metal powder, and ceramic paste. Printers vary in dimension, starting as small as a microwave oven, and their prices vary considerably. Inside the catalog of US printer maker Stratasys, one of the world leaders, the cheapest is US$5,000 (around R$18,500), and the most expensive runs US$500,000 (approx. R$1.85 million), before taxes.

For Jorge Vicente Lopes da Silva, director of the Renato Archer Information Technology Center (CTI) in Campinas São Paulo, additive manufacturing is not—nor will it become—a substitute for traditional production in most industries, but is rather a solution for market niches. The technology’s advance, he believes, is irreversible. “In each new application where 3D printing is competitive, user migration is definitive,” says Silva. “Additive manufacturing now accounts for about 0.05% of global industrial output. It won’t take long to reach 5%, which will be a revolution in world manufacturing,” he predicts.

Advantages of 3D printing
One of the main advantages of manufacturing by adding material is that it gives more freedom to designers, who don’t need to develop parts according to the movement limitations of machining tools used in conventional machining processes. In addition, the technology enables the production of parts with complex, hollow (and therefore lighter) geometry, and even allows the consolidation of multiple components into a single part.

Infographic Ana Paula Campos

In the United States, General Electric’s GE Aviation unit used the technology to combine 900 parts for a helicopter engine into only 14, and according to the company’s press release the printed parts were 40% lighter and 60% cheaper. General Motors (GM), also US-based, used 3D printing to consolidate eight components of a car seat mount into one piece, which is 40% lighter and 20% stronger.

Another characteristic of additive manufacturing, notes Zancul, is that in many situations it makes low-scale production viable. The per-unit cost of manufacturing is almost the same for producing one piece or thousands of units. Thus, one challenge for the industry is to determine the volume of production that’s most economical to produce with additive manufacturing or by a traditional system, wherein scaled production dilutes costs and provides a reduction in per-unit value.

Anderson Soares, manager of Stratasys in Brasil, says the company does a detailed study of its potential customers’ production process to ensure there will be significant economic gains. “Typically, production of less than 2,000 units per month is usually advantageous in 3D,” he says. “The cost reductions at this level of production can reach 60%.” In addition to Stratasys, other major manufacturers of 3D printers are the British company Renishaw and North American firms GE Additive and 3D Systems.

CTI Renato Archer Metal parts printed at CTI Renato ArcherCTI Renato Archer

One important economic factor, says Soares, is that additive manufacturing dispenses with the production of tools such as injection molds and stamps made of plastic or aluminum, items that cost at least R$20,000—and can run as high as R$1 million—and need to be replaced as they wear out. The technique also provides agility. In the traditional system, each manufacturing branch of a company must have its own mold of a new part before it can be reproduced. With 3D printing, headquarters sends the software with the approved design via internet, which can then be printed simultaneously and immediately in several locations.

The Brazilian unit of ThyssenKrupp Elevadores employs 3D printing to produce models of elevator button panels and spare parts for products that are already out of manufacture, reducing the cost of maintenance and modernization of older equipment. The company also uses this technology to reduce the time needed to launch new products. The new designs are sent by electronic file to its subsidiaries throughout Latin America so the molds for the new parts can be printed locally.

The Institute of Advanced Studies (IEAv), a research unit of the Brazilian Air Force’s Department of Aerospace Science and Technology (DCTA-FAB) uses 3D printing in the production of a hypersonic aeronautical engine known as a scramjet (supersonic combustion ramjet), with the aim of reducing costs. The compression stage, which captures atmospheric air for the combustor (the part of the engine where the combustion occurs), the combustor itself, and the acceleration nozzle for the combustion fuels are made using additive manufacturing. The scramjet is expected to be tested in 2020 (see Pesquisa FAPESP issue no. 275).

Léo Ramos Chaves A Stratasys technician checks the finish on a cube made by a 3D printerLéo Ramos Chaves

CTI Renato Archer is one of the biggest distributors of 3D printing in Brazil and also one of the country’s pioneers in the technology, having first created a laboratory for this purpose in 1996. The following year, it imported the first 3D printer to go into service in the country. Today, it has a Center for Three-Dimensional Technologies (NT3D) where it implements three programs for additive manufacturing research, development, and application; one oriented towards industry, another for medicine and health, and a third for scientific research.

More than 1,000 Brazilian companies of differing sizes from various sectors of activity have developed their first 3D-printing-based prototypes and products with the support of the NT3D. “With our equipment we’ve printed structures that mimic the pre-salt rock so Petrobras could study the flow of liquid through porous material,” observes director Lopes da Silva.

One current development is a hybrid system, which combines metal additive manufacturing and traditional machining in one piece of equipment. The research project, supported by FAPESP, is the result of a partnership between CTI Renato Archer, IEAv, the São Carlos School of Engineering (EESC-USP), the Technological Research Institute (IPT), the University of Campinas (UNICAMP) and the Romi industrial equipment firm of Santa Bárbara d’Oeste, in the state of São Paulo.

Léo Ramos Chaves Bicycle saddle printed with two different types of resin using additive manufacturingLéo Ramos Chaves

Reginaldo Coelho, project coordinator and a professor of production engineering at EESC-USP, explains that there is currently equipment on the market which use two different 3D-printing processes for metals. One is called Powder Bed Fusion (PBF), which fuses sequential layers of a metal bed by using a laser beam, and the other is Direct Energy Deposition (DED), which simultaneously uses lasers and metallic powder, injected into a pool of molten metal on a piece’s surface. During printing, the metal powder is melted, deposited in layers, cooled, and solidified, creating the metal piece. “Because these parts don’t yet have an adequate finish for high-performance applications, they go through a machining process,” he explains. “The hybrid equipment, produced in partnership with Romi, will allow the advantages of the two systems to be combined, that is, the production of parts with complex geometries, dispensing with molds and stamping, but with a superior finish, a characteristic of the machining process.” The first version of the equipment was launched by Romi in 2017, with two heads—one performing additive manufacturing and the other machining—operating side by side. Researchers are now working on a second-generation machine with an interchangeable head that will do both.

Bioengineering
The healthcare sector has also benefited from advances in additive manufacturing. 3D printers are used in the production of biomodels that help with planning complex surgeries, in the preparation of tools and prostheses and personalized orthotics, and even in the biofabrication of human tissues. “Today it’s possible to produce human tissue for testing new drugs and cosmetics,” says Lopes da Silva.

A fundamental role for 3D printing in the medical sector is the development of accurate digital models. CTI Renato Archer became an exemplar at the task when it created InVesalius, the first open-source software in the world that performs the reconstruction of images originating from CT or MRI devices, and integrating them with 3D printers. InVesalius now has users in 155 countries.

USP / GPHANTOM Three-dimensional cranium template of conjoined twins made using images from magnetic resonance imaging and computed tomographyUSP / GPHANTOM

At the Institute of Chemistry of the State University of São Paulo (UNESP), Araraquara campus, a group coordinated by Professor Antonio Carlos Guastaldi uses InVesalius in a project to use additive manufacturing to create bone tissue. The goal is to produce a synthetic bone scaffold and analyze the impact of sterilization on the piece, and how it interacts with human cells. Scaffolds are three-dimensional structures implanted in the body to be regenerated. Their main function is to provide mechanical and physico-chemical support for the development of new tissue.

As Guastaldi explains, a scaffold printed in 3D—based on computed tomography and magnetic resonance images—uses a bioabsorbable polymer whose function is to support calcium phosphate, a necessary element for the regeneration of bone tissue. The most common regeneration technique today requires the use of autogenous bone, coming from the person undergoing treatment. However, autogenous material is available only in small quantities. It needs to be removed from the mandible or iliac bone, requiring two surgeries, one to collect the material and another to implant it. “3D printing allows a scaffold of a precise size to be produced, with low risk of rejection by the body, and reduces the surgical procedures to just one,” he says.

At the Hospital das Clínicas in Ribeirão Preto, São Paulo, 3D printing played a key role in training the team led by neurosurgeon Hélio Rubens Machado, and in planning each stage of the operation that separated the two-year-old conjoined twins Maria Ysabelle and Maria Ysadora, who were joined at the skull. The process required five surgical procedures, performed between February and October 2018. Working together in Ribeirão Preto, the USP Physics Department and startup firm Gphantom—incubated at the Supera Innovation and Technology Park—employed additive manufacturing to develop three-dimensional models with physical and morphological properties equivalent to those of biological tissues. The modeling allowed the team to simulate each step, which reduced risks in cranial cutting and restructuring. “It was the first time this separation procedure was performed in Brazil, and we were able to simulate each surgical step in detail,” says Adilton Carneiro, coordinator of the Group of Innovation in Medical Instrumentation and Ultrasound of the USP Physics Department.

Carneiro, who is also the CEO of the Institute for Advanced Studies on Health Foundation (FIPASE) which manages the Supera Park, explains that producing a traditional mold of the sisters’ head with a mechanical lathe would have taken around 30 days, involving the collaboration of a designer, engineer, and a lathe operator, which would have cost around R$100,000. The result would be a mold of the outer area of the cranium. Each three-dimensional printed version made of polymeric material cost around R$120 and took one day to be made, based on the reproduction of accurate external and internal images of the cranium. The simulation of each stage of the operation allowed doctors to detect in advance that the girls’ skin would need to be expanded to cover their post-surgical craniums, leading the team to revise their plan in relation to the positioning and volume of the tissue expanders to be inserted. The twins, now separated, were discharged from the hospital in late 2018.

Projects
1. Study, development and application of hybrid process: Additive manufacturing (MA) + high-speed machining/grinding (HSM/G) (nº 16/11309-0); Grant Mechanism Thematic Project; Principal Investigator Reginaldo Teixeira Coelho (USP); Investment R$7,285,649.01.
2. Synthetic biological tissue simulators for training in ultrasound-guided medical procedures: Amniocentesis (nº 17/50185-8); Grant Mechanism Innovative Research in Small Business (PIPE) program; Principal Investigator Felipe Wilker Grillo (Gphantom); Investment R$330,513.11.

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